He will have soldered the connections, the original used an interference contact, eg. just touching, hence very unreliable.I've had 3 of these over a period of many years and by a long way the best (most consistent readings - others needed a good rev to give accurate readings once - and only once per journey - the engine got hot) has been the last one (fitted a couple of years ago) which was a unit that David Askew had reconditioned. See if he's still reconditioning them.